Just call me Sean

iTrader: (1)

That chart still isn't accurate to the pressures I get, unless I'm remembering wrong. It has been a while, but I get at least 30 on the low side.

Bennyv83

How is that chart not accurate then? It's a 134a chart.... What gas are you using??

Like I said, 45psi on the suction side is a good place to start.
If the OP is using part-store propane based refrigerants, then the chart he'll wanna use will be closer to R22.

Just call me Sean

iTrader: (1)

I just said it's not accurate for me, not that it's wrong. I'm in Florida, 90 plus degree weather and 100% humidity.

steve491

The chart I posted is a generic chart for R134a based on ambient temperature. Each system has different charts for best performance. For example: A Honda Civic with a very small cabin and a small grill will have a different requirement than a conversion van with 2 evaparators..
You need to have a service manual that states the pressures and cycle rates OR take it to a pro.
-Steve-

Just call me Sean

iTrader: (1)

I don't use my chart, because it's never right. I use the old temperature gauge in the vent trick.

dr_bowtie

Like I said if you add just enough refrigerant to pacify the low pressure switch at cruise speeds you WILL have the coldest AC... the higher the low side pressure the warmer the AC will blow... NOT every vehicle is a text book case and the charts are worthless...

gauges are a MUST and adding the "right" kind of freon... too many add the stuff with oil and thats bad....too much oil and the system cannot dissipate the heat...